Mesenchymal stem cells (MSCs) can differentiate into multiple cell lineages, including osteoblasts and adipocytes. We reported previously that glucocorticoid-induced leucine zipper (GILZ) inhibits peroxisome proliferator-activated receptor ␥-2 (Ppar␥2) expression and blocks adipocyte differentiation. Here we show that overexpression of GILZ in mouse MSCs, but not MC3T3-E1 osteoblasts, increases alkaline phosphatase activity and enhances mineralized bone nodule formation, whereas knockdown of Gilz reduces MSC osteogenic differentiation capacity. Consistent with these observations, real-time reverse transcription-PCR analysis showed that both basal and differentiation-induced transcripts of the lineage commitment gene Runx2/Cbfa1, as well as osteoblast differentiation marker genes including alkaline phosphatase, type I collagen, and osteocalcin, were all increased in GILZ-expressing cells. In contrast, the mRNA levels of adipogenic Ppar␥2 and C/ebp␣ were significantly reduced in GILZ-expressing cells under both osteogenic and adipogenic conditions. Together, our results demonstrate that GILZ functions as a modulator of MSCs and that overexpression of GILZ shifts the balance between osteogenic and adipogenic differentiation of MSCs toward the osteogenic pathway. These data suggest that GILZ may have therapeutic value for stem cell-based therapies of metabolic bone diseases, such as fracture repair.Bone marrow-derived mesenchymal stem cells (MSCs) 3 are pluripotent and can give rise to several distinct cell lineages, such as osteoblasts, adipocytes, chondrocytes, myocytes, and even neurons under appropriate conditions (1-4). Increasing evidence has shown that adipocytes and osteoblasts are two major pathways and that the relationship between these two is reciprocal, i.e. when the adipogenic pathway is blocked, the MSCs enter the osteogenic pathway, and vice versa (5-9). Thus, balanced MSC osteoblast and adipocyte differentiation is critical for the maintenance of healthy bone and lean body composition, and understanding of the mechanisms by which this balance is modulated will have significant medical implications in stem cell-based therapies. We reported previously that a glucocorticoid (GC)-inducible protein, called GC-induced leucine zipper (GILZ) (10), can inhibit the transcription of a key adipogenic regulator, peroxisome proliferator-activated receptor ␥-2 (Ppar␥2), and blocks adipocyte differentiation of 3T3-L1 cells (11). Gilz is a new member of the leucine zipper protein family and belongs to the transforming growth factor ␤-stimulated clone-22 (Tsc-22) family of transcription factors (12, 13). Members of this family contain three distinct domains: an N terminus TSC box, a middle leucine zipper domain, and a C terminus proline-rich domain. GILZ has been shown to interact with and inhibit the activities of the key inflammatory signaling mediators 15). GILZ can also interact with the mitogen-activated protein kinase family member, Raf1, resulting in inhibition of Raf-1 phosphorylation and, subsequently, inh...

Age-dependent bone loss has been well documented in both human and animal models. Although the underlying causal mechanisms are probably multifactorial, it has been hypothesized that alterations in progenitor cell number or function are important. Little is known regarding the properties of bone marrow stromal cells (BMSCs) or bone progenitor cells during the aging process, so the question of whether aging alters BMSC/progenitor osteogenic differentiation remains unanswered. In this study, we examined agedependent changes in bone marrow progenitor cell number and differentiation potential between mature (3 and 6 mo old), middle-aged (12 and 18 mo old), and aged (24 mo old) C57BL/6 mice. BMSCs or progenitors were isolated from five age groups of C57BL/6 mice using negative immunodepletion and positive immunoselection approaches. The osteogenic differentiation potential of multipotent BMSCs was determined using standard osteogenic differentiation procedures. Our results show that both BMSC/progenitor number and differentiation potential increase between the ages of 3 and 18 mo and decrease rapidly thereafter with advancing age. These results are consistent with the changes of the mRNA levels of osteoblast lineageassociated genes. Our data suggest that the decline in BMSC number and osteogenic differentiation capacity are important factors contributing to age-related bone loss.

Highlights Fecal SARS-CoV-2 was relevant to milder condition and better radiological recovery. The first attempt of using a survival analysis for SARS-CoV-2 RNA duration. SARS-CoV-2 RNA survival in feces was significantly longer than in oropharyngeal swabs. In spite of the negative oropharyngeal swabs, Fecal viral load easily rebounded.

Fasciclin-like arabinogalactan proteins (FLAs) are a subclass of arabinogalactan proteins (AGPs) involved in plant growth, development and response to abiotic stress. Although many studies have been performed to identify molecular functions of individual family members, little information is available on genome-wide identification and characterization of FLAs in the genus Populus. Based on genome-wide analysis, we have identified 35 Populus FLAs which were distributed on 16 chromosomes and phylogenetically clustered into four major groups. Gene structure and motif composition were relatively conserved in each group. All the members contained N-terminal signal peptide, 23 of which included predicted glycosylphosphatidylinositol (GPI) modification sites and were anchored to plasma membranes. Subcellular localization analysis showed that PtrFLA2/20/26 were localized in cell membrane and cytoplasm of protoplasts from Populus stem-differentiating xylem. The Ka/Ks ratios showed that purifying selection has played a leading role in the long-term evolutionary period which greatly maintained the function of this family. The expression profiles showed that 32 PtrFLAs were differentially expressed in four tissues at four seasons based on publicly available microarray data. 18 FLAs were further verified with qRT-PCR in different tissues, which indicated that PtrFLA1/2/3/7/11/12/20/21/22/24/26/30 were significantly expressed in male and female flowers, suggesting close correlations with the reproductive development. In addition, PtrFLA1/9/10/11/17/21/23/24/26/28 were highly expressed in the stems and differentiating xylem, which may be involved in stem development. To determine salt response of FLAs, qRT-PCR was performed to analyze the expression of 18 genes under salinity stress across two time points. Results demonstrated that all the 18 FLAs were expressed in root tissues; especially, PtrFLA2/12/20/21/24/30 were significantly induced at different time points. In summary, this study may lay the foundation for further investigating the biological functions of FLA genes in Populus trichocarpa.